U.S. Pat. No. 6,479,807 discloses a microscope allowing rapid switchover between different observation methods. Provided for this purpose is a slider on which multiple optical elements are arranged. The slider is slid completely into the microscope. A corresponding opening for receiving the slider is embodied on the microscope for this purpose. V-shaped snap-lock grooves embodied on the slider permit positioning of the optical elements in the optical axis of the microscope. Because the slider comes into contact over its entire surface with the opening embodied in the microscope for receiving the slider, low-friction guidance of the slider is definitely not present. Operation of the slider from outside the microscope is also not possible, since the position of the entire slider itself must be modified by a user, and no actuation element is present with which the user can modify the position of the slider.
U.S. Pat. No. 4,678,291 discloses an apparatus for microscopes that permits rapid switching between different observation methods. Although the optical elements are actuatable from outside the microscope, displacement of the optical elements nevertheless occurs by way of a threaded spindle, and the optical element itself is guided on a dovetail.